#include<stdio.h>
#include<malloc.h>
typedef char ElemType;
typedef struct LNode
{   ElemType data;
    struct LNode *next;
}LinkNode;
void CreatListF(LinkNode *&L,ElemType a[],int n)  //1
{   LinkNode *s;
    L=(LinkNode*)malloc(sizeof(LinkNode));
    L->next=NULL;
    for(int i=0;i<n;i++)
    {   s=(LinkNode*)malloc(sizeof(LinkNode));
        s->data=a[i];
        s->next=L->next;
        L->next=s;
    }
}
void CreatListR(LinkNode *&L,ElemType a[],int n)  //2
{   LinkNode *s,*r;
    L=(LinkNode*)malloc(sizeof(LinkNode));
    L->next=NULL;
    r=L;
    for(int i=0;i<n;i++)
    {   s=(LinkNode*)malloc(sizeof(LinkNode));
        s->data=a[i];
        r->next=s;
        r=s;
    }
    r->next=NULL;
}
void InitList(LinkNode *&L) //3
{
    L=(LinkNode*)malloc(sizeof(LinkNode));
    L->next=NULL;
}
void DestroyList(LinkNode *L) //4
{
    LinkNode *pre=L,*p=pre->next;
    while(p!=NULL)
    {
        free(pre);
        pre=p;
        p=pre->next;
    }
    free(pre);
}

bool ListEmpty(LinkNode *L) //5
{
    return(L->next==NULL);
}
int ListLength(LinkNode *L) //6
{
    int i=0;
    LinkNode *p=L;
    while(p->next!=NULL)
    {
        i++;
        p=p->next;
    }
    return(i);
}
void DispList(LinkNode *L) //7
{
    LinkNode *p=L->next;
    while(p!=NULL)
    {
        printf("%c",p->data);
        p=p->next;
    }
    printf("\n");
}
bool GetElem(LinkNode *L,int i,ElemType &e)  //8
{
    int j=0;
    LinkNode *p=L;
    if(i<=0)return false;
    while(j<i&&p!=NULL)
    {
        j++;
        p=p->next;
    }
    if(p==NULL)
        return false;
    else
    {
        e=p->data;
        return true;
    }
}
int LocateElem(LinkNode *L,ElemType e) //9
{
    int i=1;
    LinkNode *p=L->next;
    while(p!=NULL&&p->data!=e)
    {
        p=p->next;
        i++;
    }
    if(p==NULL)
        return (0);
    else
        return(i);
}
bool ListInsert(LinkNode *&L,int i,ElemType e) //10
{
    int j=0;
    LinkNode *p=L,*s;
    if(i<=0)return false;
    while(j<i-1&&p!=NULL)
    {
        j++;
        p=p->next;
    }
    if(p==NULL)
        return false;
    else
    {
        s=(LinkNode *)malloc(sizeof(LinkNode));
        s->data=e;
        s->next=p->next;
        p->next=s;
        return true;
    }
}
bool ListDelete(LinkNode *&L,int i,ElemType &e) //11
{
    int j=0;
    LinkNode *p=L,*q;
    if(i<=0)return false;
    while(j<i-1&&p!=NULL)
    {
        j++;
        p=p->next;
    }
    if(p==NULL)
        return false;
    else
    {
        q=p->next;
        if(q==NULL)
            return false;
        e=q->data;
        p->next=q->next;
        free(q);
        return true;
    }
}

int main()
{
	LinkNode *h;
	ElemType e;
	printf("单链表的基本运算如下:\n");
	printf("  (1)初始化单链表h\n");
	InitList(h);
	printf("  (2)依次采用尾插法插入a,b,c,d,e元素\n");
	ListInsert(h,1,'a');
	ListInsert(h,2,'b');
	ListInsert(h,3,'c');
	ListInsert(h,4,'d');  
	ListInsert(h,5,'e');
	printf("  (3)输出单链表h:");
	DispList(h);
	printf("  (4)单链表h长度:%d\n",ListLength(h));
	printf("  (5)单链表h为%s\n",(ListEmpty(h)?"空":"非空"));
	GetElem(h,3,e);
	printf("  (6)单链表h的第3个元素:%c\n",e);
	printf("  (7)元素a的位置:%d\n",LocateElem(h,'a'));
	printf("  (8)在第4个元素位置上插入f元素\n");
	ListInsert(h,4,'f');
	printf("  (9)输出单链表h:");
	DispList(h);
	printf("  (10)删除h的第3个元素\n");
    	ListDelete(h,3,e);
	printf("  (11)输出单链表h:");
	DispList(h);
	printf("  (12)释放单链表h\n");
	DestroyList(h);
	return 1;
}